Sidewall Image Transfer (SIT) is a process module that doubles the density of a line pattern and is thereby very important to continued silicon technology scaling. The SIT module conventionally involves the conformal deposition of a SIT spacer (for example, silicon nitride) over a previously patterned SIT mandrel at high temperatures. This high temperature deposition severely limits the use of SIT.
Specifically, due to the high processing temperatures in conventional SIT, only high-temperature-compatible materials may be used prior to the SIT steps being performed. Similarly, only high-temperature-compatible mandrels can be used as part of the SIT module. Accordingly, SIT can only be integrated into otherwise high-temperature compatible process flows, for example, excluding SIT from back-end of the line (BEOL) patterning.
Therefore, improved SIT techniques that avoid the high-temperature-compatibility problems described above would be desirable.